Cached phy register data access

ABSTRACT

Ethernet physical sublayer (PHY) devices each provide PHY register data. One or more of the Ethernet PHY devices are connected to each of one or more management data input/output (MDIO)/management data clock (MDC) interfaces to which a number of MDIO/MDC controllers are connected. Each MDIO/MDC controller polls a corresponding MDIO/MDC interface to receive the PHY register data from the one or more Ethernet PHY devices connected thereto. The MDIO/MDC controllers store portions of the PHY register data received from the Ethernet PHY devices to a memory to which an interface is connected. A processor connected to the interface accesses the portions of the PHY register data stored to the memory. The processor can retrieve the portions of the PHY register data over the interface more quickly than the MDIO/MDC controllers can retrieve the PHY register data over the MDIO/MDC interfaces.

BACKGROUND

Ethernet has evolved to meet the growing demands of packet-switchednetworks. It has become the unifying technology enabling communicationsvia the Internet and other networks using the Internet Protocol (IP).Due to its proven low cost, known reliability, and simplicity, themajority of today's Internet traffic starts or ends on an Ethernetconnection. This popularity has resulted in a complex ecosystem amongcarrier networks, enterprise networks, and consumers, creating asymbiotic relationship among its various parts.

Devices that have Ethernet capability include Ethernet physical sublayer(PHY) devices that adhere to an Ethernet standard. Ethernet PHY devicesprovide management information, which are referred to herein as PHYregister data, indicating their status, configuration, control, andother parameters via management data input/output (MDIO)/management dataclock (MDC) interfaces. MDIO is also referred to as a serial managementinterface (SMI), or media-independent interface management (MIIM), andis defined by the IEEE 802.3 Ethernet standard for a media independentinterface (MII).

SUMMARY

An example device of the disclosure includes Ethernet physical sublayer(PHY) devices. Each Ethernet PHY device has PHY registers. The deviceincludes one or more management data input/output (MDIO)/management dataclock (MDC) interfaces. One or more Ethernet PHY devices of the EthernetPHY devices are connected to each MDIO/MDC interface. The deviceincludes MDIO/MDC controllers. Each MDIO/MDC controller is connected toand is to poll a corresponding MDIO/MDC interface of the MDIO/MDCinterfaces to receive the PHY register data from the one or moreEthernet PHY devices connected to the corresponding MDIO/MDC interface.The device includes a memory to which the MDIO/MDC controllers are tostore portions of the PHY register data received from the Ethernet PHYdevices. The device includes an interface connected to the memory. Thedevice includes an interface that connects to a processor, and throughwhich the processor accesses the PHY register data stored to the memory.

An example apparatus of the disclosure includes MDIO/ MDC controllers.Each MDIO/MDC controller is connectable to a corresponding MDIO/MDCinterface of one or more MDIO/MDC interfaces to receive/set PHY registerdata from one or more Ethernet PHY devices connected to thecorresponding MDIO/MDC interface. The example apparatus includes amemory to which the MDIO/MDC controllers are to store portions of thePHY register data received from the Ethernet PHY devices. The memory isconnectable to an interface by which a processor is to access the PHYregister data stored to the memory.

An example method of the disclosure includes polling, by each MDIO/MDCcontroller of a number of MDIO/MDC controllers, one or more Ethernet PHYdevices over a corresponding MDIO/MDC interface of one or more MDIO/MDCinterfaces. The method includes, after polling the one or more EthernetPHY devices, receiving, by each MDIO/MDC controller, PHY register datafrom the one or more Ethernet PHY devices connected to the correspondingMDIO/MDC interface. The method includes, after receiving the PHYregister data, storing, by each MDIO/MDC controller, portions of the PHYregister data to a memory to which the MDIO/MDC controllers areconnected and to which an interface is connected, for access by aprocessor connected to the interface.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The drawings referenced herein form a part of the specification.Features shown in the drawing illustrate only some embodiments of thedisclosure, and not of all embodiments of the disclosure, unless thedetailed description explicitly indicates otherwise, and readers of thespecification should not make implications to the contrary.

FIG. 1 is a diagram of an example device by which an apparatus like afield-programmable gate array (FPGA) or a complex programmable logicdevice (CPLD) is used to gather physical sublayer (PHY) register datafrom Ethernet physical sublayer (PHY) devices and to store portions ofthe PHY register data to a memory accessible over an interface.

FIG. 2 is flowchart of a method by which PHY register data is retrieved,stored, and accessed within the example device of FIG. 1.

DETAILED DESCRIPTION

The following detailed description of exemplary embodiments of thedisclosure refers to the accompanying drawings that form a part of thedescription. The drawings illustrate specific exemplary embodiments inwhich the disclosure may be practiced. The detailed description,including the drawings, describes these embodiments in sufficient detailto enable those skilled in the art to practice the disclosure. Thoseskilled in the art may further utilize other embodiments of thedisclosure, and make logical, mechanical, and other changes withoutdeparting from the spirit or scope of the disclosure. Readers of thefollowing detailed description should, therefore, not interpret thedescription in a limiting sense, and only the appended claims define thescope of the embodiment of the disclosure.

As noted in the background section, devices that have Ethernetcapability include Ethernet physical sublayer (PHY) devices that adhereto an Ethernet standard. The Ethernet PHY devices provide managementinformation via management data input/output (MDIO)/management dataclock (MDC) interfaces. In this manner, the Ethernet PHY devices can bepolled to ensure, for instance, that they are operating and/orconfigured correctly.

The MDIO/MDC interface, however, is a processor-intensive, low-bandwidthinterface. A data clock—the MDC—has to be asserted on the MDIO/MDCinterface. Polling an Ethernet PHY device on the MDIO/MDC interfacetakes time, at least because of the low bandwidth of the interface. Assuch, a processor may have to apportion an undesirable amount ofprocessing power to constantly receive management information updatesfrom its Ethernet PHY devices.

Furthermore, a given device may have multiple Ethernet PHY devices thateach have multiple MDIO/MDC interfaces. The same physical bus of thedevice cannot typically be used for a large number of MDIO/MDCinterfaces, due to signal integrity issues. Inclusion of a multiplexerresolves this problem, but increases the length of time needed for theprocessor to obtain the desired management information.

An additional problem is that different MDIO/MDC interfaces can operatein accordance with different MDIO/MDC protocols that require theinterfaces to operate at different voltages. Common MDIO/MDC protocolsinclude those referred to under the nomenclature Clause 22 and Clause45. Some Ethernet PHY devices can only support some voltages, but agiven device may require that all its MDIO/MDC interfaces operate at thesame voltage and not on a per-interface basis.

Disclosed herein are techniques that alleviate these shortcomings. Anapparatus, such as in the form of a field-programmable gate array (FPGA)or a complex programmable logic device (CPLD), includes multipleMDIO/MDC controllers and a memory. Each MDIO/MDC controller is connectedto a corresponding MDIO/MDC interface of a device, to receive/set PHYregister data from one or more Ethernet PHY devices connected to thisinterface. The MDIO/MDC controllers store portions of the PHY registerdata to the memory, which is connectable to an interface by which aprocessor of the device accesses these PHY register data portions.

The processor therefore does not directly communicate with the EthernetPHY devices over the MDIO/MDC interfaces to receive managementinformation. Rather, the MDIO/MDC controllers do. As such, lessprocessing power is used by the processor to receive this information.Furthermore, the interface can permit the processor to receive themanagement information from all or at least a large number of theEthernet PHY devices within a single access. For instance, the interfacemay be a parallel bus, or a high-speed interface, such as a high-speedserial interface or bus like a peripheral component interconnect (PCI)serial bus or a peripheral component interconnect express (PCIe) serialbus. This increases the speed at which the management information isretrieved.

Furthermore, the PHY devices can be configured with specific registersettings through commands written to the memory. The MDIO/MDCcontrollers interpret and act upon these commands to appropriatelyconfigure the PHY devices. The processor thus indirectly communicateswith the PHY devices in this matter, through the memory and the MDIO/MDCcontrollers.

The different MDIO/MDC interfaces can operate at different voltages, andthus in accordance with different MDIO/MDC protocols, because theMDIO/MDC controllers are separately configurable in this respect. Assuch, connectivity to a greater diversity of different types of EthernetPHY devices can be included in the same device, without concern thatthey may have incompatible operating voltages. A large number ofEthernet PHY devices can also be employed without the need for amultiplexer interfacing the processor thereto.

FIG. 1 shows an example device 100. The networking device 100 may be anetworking device like a switching device, a routing device, a bridgingdevice, another type of networking device, or another type of device.For example, the device 100 may be a computing device like a servercomputing device or a client computing device.

The device 100 includes Ethernet PHY devices 102A, 102B, . . . , 102N,which are collectively referred to as the Ethernet PHY devices 102. EachEthernet PHY device 102 provides the device 100 with Ethernetconnectivity over a separate Ethernet networking channel or lane. Thedevice 100 includes MDIO/MDC interfaces 104A, 104B, . . . , 104N, whichare collectively referred to as the MDIO/MDC interfaces 104. EachMDIO/MDC interface 104 is a serial bus that is governed by an Ethernetstandard for the communication of PHY register data from and to theEthernet PHY devices 102.

In the example of FIG. 1, each Ethernet PHY device 102 is connected to acorresponding MDIO/MDC interface 104 on a one-to-one basis. However,more generally, one or more Ethernet PHY devices 102 can be connected toeach MDIO/MDC interface 104. As such, the relationship between theEthernet PHY devices 102 and each MDIO/MDC interface 104 can bemany-to-one.

The device 100 includes one or more MDIO/MDC controllers 106A, 106B, . .. , 106N, which are collectively referred to as the MDIO/MDC controllers106. Each MDIO/MDC controller 106 is connected to a correspondingMDIO/MDC interface 104 on a one-to-one basis in the example of FIG. 1.An MDIO/MDC controller 106 polls its corresponding MDIO/MDC interface104 to receive PHY register data from the Ethernet PHY device 102connected to this interface 104.

The MDIO/MDC controllers 106 are separately configurable to operate inaccordance with different MDIO/MDC protocols having different voltagelevels at which the MDIO/MDC interfaces 104 can operate. As such,MDIO/MDC interfaces 104 at different operating voltages can beaccommodated.

The device 100 includes a memory 108. The memory 108 along with theMDIO/MDC controllers 106 are implemented within an apparatus 114, suchas an FPGA, a CPLD, or another type of apparatus. The MDIO/MDCcontrollers 106 are connected to the memory 108, and can access thememory 108 at the same time, such that the memory 108 is shared amongthe MDIO/MDC controllers 106. Each MDIO/MDC controller 106, uponreceiving the PHY register data from the Ethernet PHY device 102connected to the same MDIO/MDC interface 104 to which the controller 106in question is connected, extracts management information regarding thedevice 102 and stores this portion of the PHY register data to thememory 108.

The device 100 includes an interface 110. The interface 110 can be aparallel bus, or a high-speed serial interface or bus like a PCI bus ora PCIe bus. A parallel bus is parallel in that multiple bitscorresponding to the bit width of the bus can be retrieved in the sameaccess (i.e., clock cycle) of the bus. The bit width of the bus may beeight bits, sixteen bits, thirty-two bits, or another number of bits.The interface 110 is connected to the memory 108. In this respective,the memory 108, in addition to being shared memory, is dual port memory,where one port of the memory 108 provides for access thereto by theMDIO/MDC controllers 106, and the other port of the memory provides foraccess thereto over the interface 110.

The device 100 includes a processor 112, such as a central processingunit (CPU) and/or a microprocessor. The processor 112 performs logic tocontrol the functionality, such as configuration, routing, switching,and so on, of the device 100. To this end, the processor 112 relies uponmanagement information, such as status and configuration parametersand/or information, which the Ethernet PHY devices 102. Therefore, theprocessor 112 accesses the memory 108 over the interface 110 to retrievethe management information previously stored to the memory 108 by theMDIO/MDC controllers 106.

Because the interface 110 and the memory 108 can be specified within thedevice 100 apart from any standard, the interface 110 may be able tooperate at a higher bandwidth than the bandwidth of the MDIO/MDCinterfaces 104, which are governed by an Ethernet standard. Therefore,retrieval of the management information over the interface 110 by theprocessor 112 can occur more quickly than retrieval of the PHY registerdata itself over the MDIO/MDC interfaces 104 by the MDIO/MDC controllers106. Each MDIO/MDC controller 106 drives an MDC and MDIO signal on itscorresponding MDIO/MDC interface 104 at a clock rate governed by anEthernet standard from which it cannot deviate, and in accordance withwhich the Ethernet PHY device 102 connected to the interface 104 inquestion provides the PHY register data.

Depending on the number of the Ethernet PHY devices 102 and/or the bitwidth of the interface 110 where the interface 110 is a parallel bus,the processor 112 may be able to access the portions of the PHY registerdata stored by the MDIO/MDC controllers 106 to the memory 108 within asingle access of the interface 110. For instance, if the parallel bus isthirty-two bits in width, if there are less than thirty-two Ethernet PHYdevices 102, and if the management information stored to the memory 108is just one bit in size for each PHY device 102, then in a single clockcycle the processor 112 can access the management information regardingall the devices 102. The processor 112 further can access the portionsof the PHY register data stored to the memory 108 on an as-needed basis,instead of having to adhere to an Ethernet standard for the MDIO/MDCinterfaces 104.

FIG. 2 shows an example method 200 as to how PHY register data isaccessed within the device 100. The blocks of FIG. 2 are divided intocolumns corresponding to the Ethernet PHY devices 102, the MDIO/MDCcontrollers 106, and the processor 112. The functionality of each blockis performed by the component corresponding to the column in which theblock in question is located.

Each MDIO/MDC controller 106 drives an MDC and MDIO signal on itscorresponding MDIO/MDC interface 104 (202). The MDC is a clock signal inaccordance with which communication between the Ethernet PHY device 102and the MDIO/MDC controller 106 occurs on the MDIO/MDC interface 104.Each MDIO/MDC controller 106 polls the Ethernet PHY device 102 connectedto its MDIO/MDC interface 104 over the interface 104 (204). Thispolling, as well as other communication, can occur in parallel among theMDIO/MDC controllers 106 over their respective MDIO/MDC interfaces 104.That is, communication over each MDIO/MDC interface 104 is separate andindependent from communication occurring over each other interface 104.

In response to being polled, each Ethernet PHY device 102 transmits itscurrent PHY register data over the MDIO/MDC interface 104 to theMDIO/MDC controller 106 connected to the interface 104 in question(206). Each MDIO/MDC controller 106 thus receives PHY register data fromthe Ethernet PHY device 102 to which it is communicatively connectedwith over an MDIO/MDC interface 104 (208).

The PHY register data is raw data, and can and typically does includeinformation that is not needed or that is irrelevant to the type ofmanagement that is to occur of the Ethernet PHY devices 102. Therefore,each MDIO/MDC controller 106 parses its received PHY register data toextract just the relevant management information that may be desired(210), and stores the extracted management information to the memory 108(212).

The processor 112, therefore, can independently, as desired, and/or asneeded retrieve this management information from the memory 108 over theinterface 110 (214). The processor 112 is thus not unencumbered byhaving to retrieve the (raw) PHY data from the Ethernet PHY devices 102itself, and does not have to itself communicate over the MDIO/MDCinterfaces 104. Rather, this functionality is effectively offloaded tothe MDIO/MDC controllers 106. The processor instead can quickly accessthe management information that the MDIO/MDC controllers 106 hasprepared, directly from the memory 108 over a faster interface 110.

It is noted that, as can be appreciated by one those of ordinary skillwithin the art, aspects of the present invention may be embodied as asystem, method or computer program product. Accordingly, aspects of theembodiments of the invention may take the form of an entirely hardwareembodiment, an entirely software embodiment (including firmware,resident software, micro-code, etc.) or an embodiment combining softwareand hardware aspects that may all generally be referred to herein as a“circuit,” “module” or “system.” Furthermore, aspects of the presentinvention may take the form of a computer program product embodied inone or more computer readable medium(s) having computer readable programcode embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium include the following: an electrical connection havingone or more wires, a portable computer diskette, a hard disk, a randomaccess memory (RAM), a read-only memory (ROM), an erasable programmableread-only memory (EPROM or Flash memory), an optical fiber, a portablecompact disc read-only memory (CD-ROM), an optical storage device, amagnetic storage device, or any suitable combination of the foregoing.In the context of this document, a computer readable storage medium maybe any tangible medium that can contain, or store a program for use byor in connection with an instruction execution system, apparatus, ordevice.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device. Program codeembodied on a computer readable medium may be transmitted using anyappropriate medium, including but not limited to wireless, wireline,optical fiber cable, RF, etc., or any suitable combination of theforegoing.

In general, a computer program product includes a computer-readablemedium on which one or more computer programs are stored. Execution ofthe computer programs from the computer-readable medium by one or moreprocessors of one or more hardware devices causes a method to beperformed. For instance, the method that is to be performed may be oneor more of the methods that have been described above.

The computer programs themselves include computer program code. Computerprogram code for carrying out operations for aspects of the presentinvention may be written in any combination of one or more programminglanguages, including an object oriented programming language such asJava, Smalltalk, C++ or the like and conventional procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The program code may execute entirely on the user's computer,partly on the user's computer, as a stand-alone software package, partlyon the user's computer and partly on a remote computer or entirely onthe remote computer or server. In the latter scenario, the remotecomputer may be connected to the user's computer through any type ofnetwork, including a local area network (LAN) or a wide area network(WAN), or the connection may be made to an external computer (forexample, through the Internet using an Internet Service Provider).

Aspects of the present invention have been described above withreference to flowchart illustrations and/or block diagrams of methods,apparatus (systems) and computer program products according toembodiments of the invention. It will be understood that each block ofthe flowchart illustrations and/or block diagrams, and combinations ofblocks in the flowchart illustrations and/or block diagrams, can beimplemented by computer program instructions. These computer programinstructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The flowchart and block diagrams in the figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

It is finally noted that, although specific embodiments have beenillustrated and described herein, it will be appreciated by those ofordinary skill in the art that any arrangement calculated to achieve thesame purpose may be substituted for the specific embodiments shown. Thisapplication is thus intended to cover any adaptations or variations ofembodiments of the present invention. As such and therefore, it ismanifestly intended that this invention be limited only by the claimsand equivalents thereof

We claim:
 1. A device comprising: a plurality of Ethernet physicalsublayer (PHY) devices, each Ethernet PHY device to provide PHY registerdata; one or more management data input/output (MDIO)/management dataclock (MDC) interfaces, one or more Ethernet PHY devices of the EthernetPHY devices connected to each MDIO/MDC interface; a plurality ofMDIO/MDC controllers, each MDIO/MDC controller connected to and to polla corresponding MDIO/MDC interface of the MDIO/MDC interfaces to receivethe PHY register data from the one or more Ethernet PHY devicesconnected to the corresponding MDIO/MDC interface; a memory to which theMDIO/MDC controllers are to store portions of the PHY register datareceived from the Ethernet PHY devices; an interface connected to thememory; and a processor connected to the interface to access theportions of the PHY register data stored to the memory.
 2. The device ofclaim 1, wherein each MDIO/MDC controller is to drive an MDC and MDIOsignal on the corresponding MDIO/MDC interface in accordance with whichthe one or more Ethernet PHY devices connected thereto provide the PHYregister data.
 3. The device of claim 1, wherein each MDIO/MDCcontroller is to, responsive to receiving the PHY register data from theone or more Ethernet PHY devices connected to the corresponding MDIO/MDCinterface, extract management information regarding the one or moreEthernet PHY devices from the PHY register data.
 4. The device of claim1, wherein each MDIO/MDC interface is a single-bit, serial bus, andwherein the interface is one of: a multiple-bit, parallel bus; aperipheral component interconnect (PCI) serial bus; a peripheralcomponent interconnect express (PCIe) bus.
 5. The device of claim 1,wherein retrieval of the PHY register data by the MDIO/MDC controllersover the MDIO/MDC interfaces occurs more slowly than retrieval of theportions of the PHY register data by the processor over the interface.6. The device of claim 1, wherein each MDIO/MDC controller is separatelyconfigurable to operate according to one of a plurality of differentMDIO/MDC protocols, each MDIO/MDC protocol having a different voltagelevel at which the MDIO/MDC interface is to operate.
 7. The device ofclaim 6, wherein at a given time, different of the MDIO/MDC controllersare operating according to different of the MDIO/MDC protocols.
 8. Thedevice of claim 1, further comprising one of a field-programmable gatearray (FPGA) and a complex programmable logic device (CPLD), withinwhich the MDIO/MDC controllers and the memory are implemented.
 9. Thedevice of claim 1, wherein the processor is to access the portions ofthe PHY register data stored to the memory for all the Ethernet PHYdevices within a single access of the interface.
 10. The device of claim1, wherein the processor is to access the portions of the PHY registerdata stored to the memory on an as-needed basis.
 11. An apparatuscomprising: a plurality of management data input/output(MDIO)/management data clock (MDC) controllers, each MDIO/MDC controllerconnectable to a corresponding MDIO/MDC interface of one or moreMDIO/MDC interfaces to receive PHY register data from one or moreEthernet physical sublayer (PHY) devices connected to the correspondingMDIO/MDC interface; and a memory to which the MDIO/MDC controllers areto store portions of the PHY register data received from the EthernetPHY devices, the memory connectable to an interface by which a processoris to access the portions of the PHY register data stored to the memory.12. The apparatus of claim 11, wherein each MDIO/MDC controller is to,responsive to receiving the PHY register data from the one or moreEthernet PHY devices connected to the corresponding MDIO/MDC interface,extract management information regarding the one or more Ethernet PHYdevices from the PHY register data.
 13. The apparatus of claim 11,wherein retrieval of the PHY register data by the MDIO/MDC controllersover the MDIO/MDC interfaces occurs more slowly than retrieval of theportions of the PHY register data by the processor from the memory. 14.The apparatus of claim 11, wherein each MDIO/MDC controller isconfigurable to operate according to one of a plurality of differentMDIO/MDC protocols, each MDIO/MDC protocol having a different voltagelevel at which the MDIO/MDC interface is to operate.
 15. The apparatusof claim 11, wherein the apparatus is implemented as one of afield-programmable gate array (FPGA) and a complex programmable logicdevice (CPLD).
 16. A method comprising: polling, by each management datainput/output (MDIO)/management data controller (MDC) controller of aplurality of MDIO/MDC controllers, one or more Ethernet physicalsublayer (PHY) devices over a corresponding MDIO/MDC interface of one ormore MDIO/MDC interfaces; after polling the one or more Ethernet PHYdevices, receiving, by each MDIO/MDC controller, PHY register data fromthe one or more Ethernet PHY devices connected to the correspondingMDIO/MDC interface; and after receiving the PHY register data, storing,by each MDIO/MDC controller, portions of the PHY register data to amemory to which the MDIO/MDC controllers are connected and to which aninterface is connected, for access by a processor connected to theinterface.
 17. The method of claim 16, further comprising: driving, byeach MDIO/MDC controller, an MDC and MDIO signal on the correspondingMDIO/MDC interface in accordance with which the one or more Ethernet PHYdevices connected thereto provide the PHY register data.
 18. The methodof claim 16, further comprising: extracting, by each MDIO/MDCcontroller, management information regarding the one or more EthernetPHY devices from the PHY register data.
 19. The method of claim 16,further comprising, in response to being polled: providing, by eachEthernet PHY device of the one or more Ethernet PHY devices, the PHYregister data over the corresponding MDIO/MDC interface.
 20. The methodof claim 16, further comprising: accessing, by the processor, theportions of the PHY register data from the memory over the interfacewithin a single access of the interface.